Aliphatic amine alkylene oxide adducts, and particularly ethylene oxide adducts are used as surfactants and raw materials thereof, and the field of application covers a wide range of applications for domestic use, industrial use, agricultural use and the like, such as surfactants, auxiliary dyes for textiles, textile softening finishes, disinfectants, agrochemical spreading agents, antistatic agents and film surface modifiers.
These aliphatic amine alkylene oxide adducts are generally produced by adding an alkylene oxide to an aliphatic amine in the absence of a catalyst or in the presence of an alkali catalyst such as a hydroxide of an alkali metal or an alkaline earth metal. It has been known for long that with an amount of addition of ethylene oxide of up to 2 moles, the degree of activity of the amino group is high, and an adduct having a satisfactory color can be obtained without a catalyst.
When a reaction is carried out in the absence of a catalyst, the raw material amine is quaternized, and also, an alkyl group is detached by Hoffman degradation, producing a substance that causes coloration. Thus, although the color is satisfactory immediately after production, coloration occurs based on daily variation.
When an alkali catalyst such as a hydroxide of an alkali metal or an alkaline earth metal is used, the color is further worsened, and particularly there is a problem that coloration becomes conspicuous as the number of added moles of ethylene oxide increases.
Furthermore, conventional reactions have a problem that an aliphatic amine in the raw material or an alkoxylate as a reaction intermediate is quaternized in the presence of a trace amount of moisture or the like, and Hoffman degradation of the quaternary ammonium salt occurs under heat, thus causing generation of impurities and broadening of the distribution of added moles of alkylene oxide. Furthermore, as the degradation products have a stimulating odor, the alkylene oxide adducts have not been put into practical use for detergent applications, and particularly for domestic detergent applications.
In order to solve such problems, there have been suggested, as methods for preventing coloration, a method of performing the reaction at low temperature (for example, Patent Document 1), a method of using a metal oxide catalyst or an acid catalyst (for example, Patent Document 2), and the like.
However, even with these methods, the chance of obtaining a color improving effect is limited only to the occasions where the number of added moles of ethylene oxide is small, so that as the number of added moles of ethylene oxide increases to more than 2 moles, the color improving effect becomes insufficient. Furthermore, when the alkylene oxide adducts are used for detergent applications, a detergent power, foaming, foam breaking and odorlessness are required, but since the substances are still unsatisfactory in terms of purity, molecular weight distribution and countermeasures against foul odor, they are not put to utilization.    Patent Document 1: JP-A No. 2003-96186    Patent Document 2: JP-A No. 2005-154370